# Online/Offline Event Detection
Online and offline event detection can be implemented in the renderer process
using standard HTML5 APIs, as shown in the following example.
_main.js_
```javascript
var app = require('app');
var BrowserWindow = require('browser-window');
var onlineStatusWindow;
app.on('ready', function() {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false });
onlineStatusWindow.loadUrl('file://' + __dirname + '/online-status.html');
});
```
_online-status.html_
```html
<!DOCTYPE html>
<html>
<body>
<script>
var alertOnlineStatus = function() {
window.alert(navigator.onLine ? 'online' : 'offline');
};
window.addEventListener('online', alertOnlineStatus);
window.addEventListener('offline', alertOnlineStatus);
alertOnlineStatus();
</script>
</body>
</html>
```
There may be instances where one wants to respond to these events in the
main process as well. The main process however does not have a
`navigator` object and thus cannot detect these events directly. Using
Electron's inter-process communication utilities, the events can be forwarded
to the main process and handled as needed, as shown in the following example.
_main.js_
```javascript
var app = require('app');
var ipc = require('ipc');
var BrowserWindow = require('browser-window');
var onlineStatusWindow;
app.on('ready', function() {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false });
onlineStatusWindow.loadUrl('file://' + __dirname + '/online-status.html');
});
ipc.on('online-status-changed', function(event, status) {
console.log(status);
});
```
_online-status.html_
```html
<!DOCTYPE html>
<html>
<body>
<script>
var ipc = require('ipc');
var updateOnlineStatus = function() {
ipc.send('online-status-changed', navigator.onLine ? 'online' : 'offline');
};
window.addEventListener('online', updateOnlineStatus);
window.addEventListener('offline', updateOnlineStatus);
updateOnlineStatus();
</script>
</body>
</html>
```